Socket for an electronic device

ABSTRACT

One embodiment of the present invention is a socket useful to contact an electronic device, the socket including: (a) one or more contactor holder plates including one or more first through holes having a first hole cross sectional area, and one or more second through holes having a second hole cross sectional area; (b) one or more first contactors having a body with a first body cross sectional area disposed in the first through holes; (c) one or more second contactors having a body with a second body cross sectional area disposed in the second through holes; and (d) a heat sink in thermal contact with one or more of the one or more contactor holder plates; wherein a first ratio of the first hole cross sectional area to the first body cross sectional area is different from a second ratio of the second hole cross sectional area to the second body cross sectional area.

This patent application relates to U.S. Provisional Application No.60/801,304 filed May 18, 2006 from which priority is claimed under 35USC §119(e), and which provisional application is incorporated herein inits entirety.

TECHNICAL FIELD OF THE INVENTION

One or more embodiments of the present invention relate to a socket foran electronic device such as a microelectronic device, and moreparticularly to a socket for supplying high current and high frequencyelectrical currents to high performance microelectronic devices, forexample, and without limitation, integrated circuits (“ICs”).

BACKGROUND OF THE INVENTION

Sockets are used widely in the electronics industry to mount and connectmicroelectronic devices such as semiconductor integrated circuits(“ICs”) to electronics systems of various sorts—as is well known, asocket is used to connect terminals on a device to correspondingcontacts on a printed circuit board or other electrical interconnectionmeans. In addition, sockets are routinely used in systems for: (a)testing electronic device performance (an assortment of socket typeshave been developed to connect to a device under test (“DUT”) having awide variety of terminals and configurations), or (b) bum-in ofelectronic devices at elevated temperatures.

Prior art sockets are differentiated typically according to deviceterminals and intended end use (i.e., application). As such, sockets aretypically designed to make electrical contact to microelectronic deviceshaving specific types of device terminals—types of device terminalscontacted by sockets include pin grid arrays (“PGAs”), J-leads,gull-wing leads, dual in-line (“DIP”) leads, ball grid arrays (“BGAs”),column grid arrays (“CGAs”), flat metal pads (“LAN” grid arrays or“LGAs”), and many others. In order to provide sockets formicroelectronic devices with this variety of terminals, many contactortechnologies have been developed for sockets. In addition to theforegoing, further differentiation among prior art sockets refers to lowinsertion force (“LIF”) sockets, zero insertion force (“ZIF”) sockets,auto-load sockets, bum-in sockets, high performance test sockets, andproduction sockets (i.e., sockets for use in products). In furtheraddition to the foregoing, low cost prior art sockets for bum-in andproduct applications typically incorporate contactors of stamped andformed springs to contact terminals on a DUT. In still further additionto the foregoing, for high pin-count prior art sockets, a cam is oftenused to urge device terminals laterally against corresponding contactorsto make good contact to each spring while allowing a low or zeroinsertion force.

For specialized applications, prior art sockets have used a wide varietyof contactors, including anisotropic conductive sheets, flat springs,lithographically formed springs, fuzz buttons (available from Cinch,Inc. of Lombard, Ill.), spring wires, barrel connectors, twisted wiresprings in an elastomer, and spring forks, among others. Prior artsockets intended for applications where many test mating cycles (alsoreferred to as socket mount-demount cycles) are required typically usespring pin contactors of the type exemplified by Pogo® spring contacts(available from Everett Charles Technologies of Pomona, Calif.). Springprobes for applications in the electronics test industry are availablein many configurations, including simple pins and coaxially groundedpins. Most prior art spring probes consist of a helical wire springdisposed between a top post (for contacting terminals on the DUT) and abottom post (for contacting contacts on a circuit board—a device undertest board or “DUT board”).

Prior art sockets typically consist of a plurality of contactorsdisposed in an array of apertures formed through a dielectric holder. Byway of example, a high performance, prior art test socket mayincorporate a plurality of Pogo® spring contacts, each of which is heldin a pin holder consisting of an array of holes through a thindielectric plate. The dielectric material in a high performance, priorart test socket is typically selected from a group of dimensionallystable polymer materials including: glass reinforced Torlon 5530available from Quadrant Engineering Plastic Products, Inc. of Reading,Pa.; Vespel; Ultem 2000 available from GE Company GE Plastics ofPittsfield, Mass.; PEEK; liquid crystal polymer; and others. Theindividual Pogo® spring contacts are typically selected and designed forsignal conduction at an impedance level of approximately fifty (50)ohms. In certain high performance, prior art configurations, thecontactor is a coaxial type having a center spring pin with a contactorbarrel body enclosed within a cylindrical, coaxial, ground shield spacedto achieve a desired signal impedance, typically fifty (50) ohms.

Materials other than dielectric sheets have been used for prior artsocket bodies. For example, ceramic materials including alumina,aluminum nitride, and low temperature co-fired ceramic are used for hightemperatures. In addition, insulation coated, metal socket bodies havebeen used to control dimensional stability over a range of temperature.In further addition, laminated bodies of alternating layers ofdielectric and metal materials in thermal contact with elastomericcontactors and compliant contactors have been used.

As is well known to those of ordinary skill in the art, a primaryfunction of prior art sockets is to provide reliable and repeatableelectrical contact to microelectronic device terminals (i.e., acapability to mount and demount a device on the socket repeatedly,without causing damage to either). As such, a measure of quality iscontact resistance between device terminals and corresponding contactson a measurement system, determined as a function of a number ofrepeated mating cycles. For example, a high performance socket willtypically provide a contact resistance of 20 milliohms or less for10,000 mating cycles. More recently, advances in semiconductor devicesare placing additional demands on IC sockets. In particular, increasingpower and current levels require sockets that can supply more currentper terminal. Further, at higher levels of current, the socket becomes asource of heat due to current flowing through the contact resistance ofeach pin. Further demands are also placed on the socket for signalperformance relating to: (a) controlled impedance for signal terminals;(b) low cross talk between signal terminals; and (c) low inductancepower and ground connections to a device.

In light of the above, despite the many socket technologies available inthe prior art, there is a need in the art for a socket that can satisfyone or more of the above-identified demands relating to high current,low impedance power and ground connections, impedance control, andisolation of high frequency signal terminals.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention satisfy one or more ofthe above-identified demands. In particular, one embodiment of thepresent invention is a socket useful to contact an electronic device,the socket comprising: (a) one or more contactor holder plates includingone or more first through holes having a first hole cross sectionalarea, and one or more second through holes having a second hole crosssectional area; (b) one or more first contactors having a body with afirst body cross sectional area disposed in the first through holes; (c)one or more second contactors having a body with a second body crosssectional area disposed in the second through holes; and (d) a heat sinkin thermal contact with one or more of the one or more contactor holderplates; wherein a first ratio of the first hole cross sectional area tothe first body cross sectional area is different from a second ratio ofthe second hole cross sectional area to the second body cross sectionalarea.

In addition, another embodiment of the present invention is a socketuseful to contact an electronic device, the socket comprising (a) one ormore electrically conductive contactor holder plates including one ormore first through holes having a first hole cross sectional area, andone or more second through holes having a second hole cross sectionalarea; (b) one or more first contactors having a body with a first bodycross sectional area disposed in the first through holes; and (c) one ormore second contactors having a body with a second body cross sectionalarea disposed in the second through holes; wherein a ratio of the firsthole cross sectional area to the first body cross sectional area isgreater than 1.4 times a ratio of the second hole cross sectional areato the second body cross sectional area.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A shows a cross sectional view of a socket that is fabricated inaccordance with one or more embodiments of the present invention;

FIG. 1B shows a cross sectional view of the socket shown in FIG. 1A inuse for testing by providing a connection between a device under test(“DUT”) and a device under test board (“DUT board”);

FIGS. 2A and 2B show a cross sectional view and a top view,respectively, of a socket that is fabricated in accordance with one ormore further embodiments of the present invention;

FIGS. 3A and 3B show a cross sectional view and a top view,respectively, of a socket that is fabricated in accordance with one ormore still further embodiments of the present invention;

FIG. 4A shows a partial sectional view of a socket that is fabricated inaccordance with one or more embodiments of the present invention whereinsignal and power/ground contactors comprise spring probes;

FIG. 4B shows a partial sectional view of a socket that is fabricated inaccordance with one or more embodiments of the present invention whereinsignal and power/ground contactors comprise spring probes inserted intoholes through a stack of several contactor holder plates;

FIG. 4C shows a partial sectional view of a socket that is fabricated inaccordance with one or more embodiments of the present invention whereinsignal and power/ground contactors comprise tubular connectors;

FIG. 4D shows a partial sectional view of a socket that is fabricated inaccordance with one or more embodiments of the present invention whereinsignal and power/ground contactors comprise tubular connectors insertedinto holes through a stack of several contactor holder plates;

FIGS. 5A-5D show partial top views of sockets that are fabricated inaccordance with one or more embodiments of the present invention havingvarious arrangements of signal contactors and power/ground contactors;

FIGS. 6A and 6B are perspective views of contactors having prongsadapted to grip a terminal bump that may be used to fabricateembodiments of the present invention; and

FIGS. 7A, 7B and 7C are perspective views of double-ended contactorshaving prongs adapted to grip a terminal bump that may be used tofabricate embodiments of the present invention.

DETAILED DESCRIPTION

FIG. 1A shows a cross sectional view of socket 10 that is fabricated inaccordance with one or more embodiments of the present invention. Inaccordance with one or more embodiments of the present invention, socket10 can be used, among other things, as a socket for contacting anintegrated circuit (“IC”) or other microelectronic or electronic device.

As shown in FIG. 1A, socket 10 comprises contactors in the form of aplurality of spring probes 24 and spring probes 30 that are held incircular, cylindrical through holes in contactor holder plates 14 and 18by dielectric sheets 20 and 22. As shown in FIG. 1A, dielectric sheets20 and 22: (a) have holes for spring pins of the spring probes (as iswell known, the term spring pin refers to a pin that protrudes from aspring probe); (b) prevent spring probes 24 and spring probes 30 frommaking contact with contactor holder plates 14 and 18; and (c) provideinsulation between socket 10 and any device or test board to whichsocket 10 may be contacted. As further shown in FIG. 1A: (a) spring pins26 and 28 of spring probes 24 and spring pins 32 and 34 of spring probes30 are biased outward of dielectric sheets 20 and 22 (the thicknesses ofcontactor holder plates 14 and 18 are sufficient to enclose the barrelbodies of spring probes 24 and 30 while enabling spring pins thereof toproject out from dielectric sheets 20 and 22); and (b) each of thethrough holes in contactor holder plates 14 and 18 have substantiallythe same diameter. Spring probes suitable for use in fabricating one ormore such embodiments of the present invention are available in manyshapes and body diameters from suppliers such as, for example andwithout limitation, Everett Charles Technologies of Pomona Calif.(“Everett Charles”), Rika Denshi America of Attleboro Mass. (“RikaDenshi”), and Interconnect Devices, Inc. (“IDI”) of Kansas City Kans.

In accordance with one or more such embodiments of the presentinvention, contactor holder plates 14 and/or 18 are thermally conductivesheets having through holes that accommodate spring probes 24 and 30. Inaccordance with one or more such embodiments of the present invention,contactor holder plates 14 and/or 18 are made of a thermally conductivematerial such as, for example and without limitation, copper, copperalloys (for example and without limitation, copper alloy 145 that isavailable from Olin Corporation of Norwalk, Conn.), bronze, copperplated, nickel-iron alloys (for example and without limitation, copperplated invar), silver alloys, aluminum, aluminum alloys, berylia,aluminum nitride, silicon, and silicon carbide. In accordance with oneor more such embodiments, the material used to fabricate contactorholder plate 14 and/or 18 is selected to have a relatively high thermalconductivity, for example and without limitation, 0.1 Watts/° C.-cm² orgreater and preferably greater than 0.3 Watts/° C.-cm². Further, inaccordance with one or more further such embodiments, contactor holderplates 14 and 18 have substantially parallel, planar major surfaces.Still further, in accordance with one or more still further suchembodiments, contactor holder plates 14 and 18 are secured together, forexample and without limitation, by bolts (not shown) which extendthrough holes formed in contactor holder late 14, and are screwed intothreaded holes formed in contactor holder plate 18.

As further shown in FIG. 1A, and in accordance with one or moreembodiments of the present invention, contactor holder plates 14 and 18may be separated by dielectric layer 16—for example and withoutlimitation, dielectric layer 16 may be present in regions which surroundspring probes 24 (as will be described below, spring probes 24 carrysignals). In accordance with one or more such embodiments of the presentinvention, dielectric layer 16 may be used to space contactor holderplates 14 and 18 to adjust a characteristic impedance of spring probes24 to a predetermined value, for example and without limitation, fifty(50) ohms where the characteristic impedance of spring probes 24 may bedetermined by, among other things, the thickness and material propertiesof contactor holder plates 14 and 18, the diameter of the through holes,the barrel body diameter of spring probes 24, the dielectric constant(s)of dielectric material(s) in the through hole, and the thickness anddielectric constant of dielectric sheet 16, if present, (wheredielectric sheet 16 may comprise one or more dielectric sheets of thesame or differing dielectric constants)—as may be calculated using anyone of a number of three dimensional field solver algorithms (forexample, the IBM Electromagnetic Field Solver Suite of Tools) that arewell known to those of ordinary skill in the art.

As further shown in FIG. 1A, and in accordance with one or moreembodiments of the present invention, contactor holder plates 14 and 18are thermally connected to heat sink 38 by clamp 36. In accordance withone or more such embodiments, heat sink 38 and clamp 36 are made of athermally conductive material such as, for example and withoutlimitation, copper, aluminum alloy 6061, or copper alloy 145, all ofwhich are commonly available. In addition, and in accordance with one ormore embodiments of the present invention, spring probes 24 and 30 maybe arranged in a pattern of impedance-controlled signal contactors andlow impedance power and ground contactors that matches that of terminalsand contacts to which socket 10 may be connected.

As shown in FIG. 1A, and in accordance with one or more embodiments ofthe present invention, the through holes in contactor holder plates 14and 18 have substantially the same diameter, and spring probes 24 and 30have different barrel body diameters. This provides a different spacingbetween the through holes and: (i) the barrel bodies of spring probes24, and (ii) the barrel bodies of spring probes 30, respectively. As aresult, and in accordance with the present invention, this provides adifference in impedance of, and thermal resistance to, contactor holderplates 14 and 18 for spring probes 24 and 30.

As further shown in FIG. 1A, each of spring probes 24 and 30 isseparated from contactor holder plates 14 and 18 by an air gap. Inaccordance with one or more further such embodiments of the presentinvention, to further avoid contact between spring probes 24 and 30 andcontactor holder plates 14 and 18, an inside surface of each throughhole in contactor holder plates 14 and 18 may be coated with a thindielectric layer such as, for example and without limitation, Parylene(available from Specialty Coating Systems of Indianapolis Ind.). Inaccordance with one or more such embodiments, a dielectric layer mayextend over all or portions of other surfaces of the contactor holderplate(s).

In accordance with one or more embodiments of the present invention,spring probes 30 may be used to contact power or ground terminals of adevice (as is well known, the term terminal refers to an electricalcontact on a device). Power and ground currents are limited typically toabout 2 to 8 amperes by the current carrying capability of springprobes. For example, a typical Pogo® spring contact can handle a maximumamount of power before it overheats, and its springs lose temper. Sincepower is determined by I²R (where I is current and R is resistance),this limitation can be translated into a limitation on current carriedby such a contactor. Thus, such contactors cannot be readily utilized inhigh power applications unless this limitation is overcome.

In accordance with one or more embodiments of the present invention,benefits may be achieved for socket 10 by having a spacing between thebarrel body of each of power and ground spring probes 30 and a surfaceof their through holes in contactor holder plates 14 and 18 that issmall. Preferably, a small spacing of about 0.1 mm provides a relativelylow thermal resistance between spring probes 30 and thermally conductivecontactor holder plates 14 and/or 18 (when compared with a thermalresistance between signal spring probes 24 and contactor holder plates14 and 18). Advantageously, this results in an enhanced thermalconductivity from power and ground spring probes to contactor holderplates 14 and 18. Thus, in accordance with the enhanced thermalconductivity provided by socket 10, the amount of current carried byspring probes 30 can be increased. As one skilled in the art willreadily appreciate, using a small spacing between a body of a signalspring probe and a through hole in a conductive body is not practicalbecause a larger spacing is typically necessary due to a requirementthat the ratio of probe body diameter to through hole diameter isdetermined by signal impedance. By way of example, an impedance of 50ohms requires that this ratio be about 2.3.

As one can readily appreciate from FIG. 1A, heat is conducted: (a)through the spacing between each contactor and its corresponding throughhole in contactor holder plates 14 and 18 and away from the contactor;(b) through contactor holder plates 14 and/or 18; (c) through clamp 36;and (d) into heat sink 38 (for example and without limitation, a thermalmass through which socket 10 is cooled). In accordance with one or moreembodiments of the present invention, thermal conductivity from springprobes 30 (used to contact power or ground terminals) to contactorholder plates 14 and 18 is high due to a small spacing between a barrelbody of spring probes 30 and a corresponding through hole in contactorholder plates 14 and 18. Further, in accordance with one or more suchembodiments of the present invention, heat may be carried away from heatsink 38 by a thermal transfer fluid flowing through channel 40 in heatsink 38. Those of ordinary skill in the art will readily appreciate thatchannel 40 may also include a multiplicity of channels designed inaccordance with any one of a number of methods well known to one ofordinary skill in the art to enable efficient transfer of heat therefromto the thermal transfer fluid. In accordance with one or more suchembodiments, such channels may be microchannels, for example and withoutlimitation, for use preferably when the thermal transfer fluid is a gas.For example and without limitation, in accordance with one or more suchembodiments, heat sink 38 comprises a block of thermally conductivematerial with microchannels for thermal transfer fluid flow within theblock. In addition, in accordance with one or more further embodimentsof the present invention, heat sink 38 a set of channels that areinterdigitated so that walls between the channels are relatively thin tomaximize thermal conductivity, reduce thermal gradients, and promoteuniform temperatures across a surface of a plate that overlays theinterdigitated channels. In accordance with one or more furtherembodiments of the present invention, the set of channels includes asingle serpentine channel that switches back and forth. In accordancewith one or more such embodiments of the present invention, the thermaltransfer fluid may be selected from a group including, but not limitedto, water, water-glycol mixtures, Fluorinert (available from 3MCorporation, St. Paul, Minn.), Galden® (available from Solvay Chemicals,Inc., Houston, Tex.), compressed air, air, nitrogen and helium. Thus, inaccordance with one or more embodiments of the present invention, springprobes 30 of socket 10 are prevented from overheating due to highcurrents passing therethrough.

In accordance with one or more embodiments of the present invention,contactor holder plates 14 and/or 18 may be electrically conductivemetallic plates. Further, spring probes 24 may be used to contact signalterminals on a device. Typically, signal connections through a socketare designed to have an electrical impedance between 20 and 100 ohms,and preferably 50 ohms. To estimate signal contactor electricalimpedance, one may use a ratio of a diameter of a through hole incontactor holder plates 14 and 18 to an average diameter of a barrelbody of spring probes 24 disposed in the through hole—taken togetherwith a design of spring probe 24 (for example, a shape of the barrelbody of spring probe 24, and electrical properties of spring probe 24),spacing to nearest neighbor contactors, and effects of variousdielectric layers such as dielectric layer 16. In applications where airfills the space in the through holes and the thickness of dielectriclayer 16 is negligible with respect to the thickness of metalliccontactor holder plates 14 and 18, the impedance of a contactor used forsignal terminals is given approximately by Z_(S)=60ln(D_(signal hole)/D_(signal body)). As such, in accordance with one ormore embodiments of the present invention, for applications where airfills the space, the diameter of a cylindrical, coaxial through hole(D_(signal hole)) in contactor holder plates 14 and 18 (when configuredas a ground shield) is about 2.3 times the diameter of the barrel body(D_(signal body)) of spring probe 24 to achieve a signal impedance of 50ohms.

Further advantages accrue for embodiments wherein contactor holderplates 14 and/or 18 are metallic due to a reduction of impedance of thepower and ground spring probes. As is well known to those of ordinaryskill in the art, a low impedance contactor is advantageous for makingpower and ground connections to a high performance device to reducenoise at the power and ground in the device caused by fluctuations inpower and ground currents.

To estimate power or ground contactor impedance, one may use a ratio ofa diameter of a through hole in contactor holder plates 14 and 18 to anaverage diameter of a barrel body of spring probes 30 disposed in thethrough hole—taken together with a design of spring probe 30 (forexample, a shape of the barrel body of spring probe 30, and electricalproperties of spring probe 30), spacing to nearest neighbor contactors,and effects of various dielectric layers such as dielectric layer 16. Inapplications where air fills the space in the through holes andcontactor holder plates 14 and 18 are metallic, the impedance of acontactor used for power or ground terminals is given approximately byZ_(P)=60 ln(D_(power hole)/D_(power body)). In this approximation,D_(power hole) is the diameter of the power or ground through hole incontactor holder plates 14 and 18, and D_(power body) is the averagediameter of the body of the power or ground contactor. As such, and inaccordance with one or more embodiments of the present invention, theimpedance of power and ground contactors is preferably no more than 80percent of the impedance of signal contactors to provide a significantreduction in power and ground characteristic impedance. In accordancewith mathematical formulations for impedance, a requirement that thepower contactor characteristic impedance be 80 percent or less than thesignal contactor characteristic impedance is approximately satisfied bya mathematical expression:(D_(signal hole)/D_(signal body))≈1.18*(D_(power hole)/D_(power body)).Equivalently, the requirement that the power contactor impedance be nogreater than 80 percent of the signal contactor impedance isapproximately satisfied by a second mathematical expression:(A_(signal hole)/A_(signal body))≈1.4*(A_(power hole)/A_(power body)).In this second mathematical expression,(A_(signal hole)/A_(signal body)) is a ratio of the cross sectional areaof the through hole for the signal contactor to the cross sectional areaof the body of the signal contactor. Correspondingly,(A_(power hole)/A_(power body)) is a ratio of the cross sectional areaof the through hole for the power or ground contactor to the crosssectional area of the body of the power or ground contactor. Further,for embodiments in which any of the through holes in the contactorholder plates or any of the contactor bodies is not a right circularcylinder, the second mathematical expression is an approximateestimation of the requirement necessary to provide that a power andground contactor has a characteristic impedance that is 80 percent orless than the characteristic impedance of a signal contactor.

As one can readily appreciate from the above, one or more embodiments ofsocket 10 that incorporate electrically conductive (for example,metallic) contactor holder plates may provide: (a) well shielded,controlled impedance, contactors for signal terminals (for example animpedance of about 50 ohms); (b) low impedance power or groundcontactors; and (c) a thermal conduction path from power or groundcontactors to a heat sink. In addition, the controlled impedance,together with electrical shielding of adjacent spring probes byelectrically conductive contactor holder plates 14 and 18, provides ahigh integrity signal path for high performance devices.

FIG. 1B shows a cross sectional view wherein socket 10 is used to testdevice under test 42 (“DUT 42”). As shown in FIG. 1B, ball grid array 44of DUT 42 is engaged with socket 10 by contact between ball grid array44 and top spring pins 26 and 32 of spring probes 24 and 30,respectively. As further shown in FIG. 1B, device under test board 46(“DUT board 46”) is engaged with socket 10 by contact between contactpads 48 of DUT board 46 (as is well known, the term contact pad refersto an electrical contact on DUT board 46) and bottom spring pins 28 and34 of spring probes 24 and 30, respectively. To effectuate thisarrangement, spring pins 28 and 34 are compressed into the bodies ofspring probes 24 and 30, respectively, as socket 10 is urged intocontact with DUT board 46. Then, DUT 42 is urged into contact withspring probes 24 and 30 of socket 10; thereby compressingcrown-shape-headed spring pins 26 and 32 into the bodies of springprobes 24 and 30, respectively. As a result, electrical contact is madebetween solder balls of ball grid array 44 of DUT 42 and spring pins 28and 32, thereby making an electrical contact between solder balls ofball grid array 44 and contact pads 48 on DUT board 46. Hence,electrical signals, and power and ground currents are conducted fromcircuits in DUT board 46 to corresponding solder balls of ball gridarray 44 on DUT 42. Contactor holder plates 14 and 18 may be grounded tothe socket case, or to either of the power or the ground spring probes.

In accordance with one or more embodiments of the present invention,each of spring probes 24 and 30 of socket 10 is mounted in a throughhole having a diameter of about 1.15 mm in contactor holder plates 14and 18. In accordance with one or more such embodiments, each of springprobes 24 (used to contact signal terminals of DUT 42) is aSingle-Ended, Mini-Mite™, Pogo probe SCP-080ZB-001 (available fromEverett Charles) that has a barrel body diameter of about 0.52 mm and alength of about 3.89 mm. Further, in accordance with one or more suchembodiments, each of spring probes 30 (used to contact power and groundterminals of DUT 42) is a Single-Ended, Mini-Mite™, Pogo probeSCP-127ZB-001 (obtainable from Everett Charles) that has a barrel bodydiameter of about 0.95 mm and a length of about 3.89 mm. Still further,in accordance with one or more such embodiments, a grid spacing betweenspring probes 24 and 30 is about 1.27 mm, and dielectric sheets 20 and22 are thin sheets of dielectric material, for example and withoutlimitation, each may be a film of polyimide flex materials having athickness of about 0.05 mm. Still further, in accordance with one ormore such embodiments, dielectric layer 16 is a polyimide sheet having athickness of about 0.1 mm.

Although the above-described embodiments used contactors of the Pogo®spring contact type, it should be understood by one of ordinary skill inthe art that this does not limit all embodiments of the presentinvention to their use. In fact, further embodiments of the presentinvention may be fabricated wherein other contactors are used such as,for example and without limitation, barrel springs available fromMill-Max Manufacturing Corp. of Oyster Bay, N.Y., contact springs,formed springs, and tubular connectors. It should be further understoodby one of ordinary skill in the art that spring probes of many shapesand specifications may be used in place of the above-described EverettCharles spring probes. Lastly, it should be understood by one ofordinary skill in the art that the spring probes shown in FIGS. 1A and1B are representations that are provided for purposes of simplifying theexplanation of the various embodiments, and that they are not an exactrepresentation of any particular spring probe.

FIGS. 2A and 2B show a cross sectional view and a top view,respectively, of socket 100 that is fabricated in accordance with one ormore further embodiments of the present invention—FIG. 2A is a crosssectional view of socket 100 in a direction indicated by arrows AA′ inFIG. 2B. In accordance with one or more embodiments of the presentinvention, socket 100 can be used, among other things, as a socket forcontacting an integrated circuit or other microelectronic or electronicdevice.

As shown in FIG. 2A, socket 100 comprises contactors 110 ₁-110 _(n) inthe form of spring probes that are held in circular, cylindrical throughholes in contactor holder plates 114 and 118 by dielectric sheets 120and 122. As shown in FIG. 2A, dielectric sheets 120 and 122: (a) haveholes for spring pins of the spring probes; (b) prevent contactors 110₁-110 _(n) from making contact with contactor holder plates 114 and 118;and (c) provide insulation between socket 100 and any device or testboard to which socket 100 may be contacted. As further shown in FIG. 2A,spring pins of contactors 110 ₁-110 _(n) are biased outward ofdielectric sheets 120 and 122 (the thicknesses of contactor holderplates 114 and 118 are sufficient to enclose the barrel bodies ofcontactors 110 ₁-110 _(n), while enabling spring pins thereof to projectout from dielectric sheets 120 and 122). Spring probes suitable for usein fabricating one or more such embodiments of the present invention areavailable in many shapes and body diameters from suppliers such as, forexample and without limitation, Everett Charles, Rika Denshi, and IDI.

In accordance with one or more such embodiments of the presentinvention, contactor holder plates 114 and/or 118 are thermallyconductive sheets having through holes that accommodate contactors 110₁-110 _(n). In accordance with one or more such embodiments of thepresent invention, contactor holder plates 114 and 118 are made of athermally conductive material such as, for example and withoutlimitation, copper, copper alloys (for example and without limitation,copper alloy 145 that is available from Olin Corporation of Norwalk,Conn.), bronze, copper plated, nickel-iron alloys (for example andwithout limitation, copper plated invar), silver alloys, aluminum,aluminum alloys, berylia, aluminum nitride, silicon, and siliconcarbide. In accordance with one or more such embodiments, the materialused to fabricate contactor holder plate 114 and/or 118 is selected tohave a relatively high thermal conductivity, for example and withoutlimitation, 0.1 Watts/° C.-cm² or greater and preferably greater than0.3 Watts/° C.-cm². Further, in accordance with one or more further suchembodiments, contactor holder plates 114 and 118 have substantiallyparallel, planar major surfaces. Still further, in accordance with oneor more still further such embodiments, contactor holder plates 114 and118 are secured together, for example and without limitation, by bolts(not shown) which extend through holes formed in contactor holder plate114 and are screwed into threaded holes formed in contactor holder plate118.

As further shown in FIG. 2A, and in accordance with one or moreembodiments of the present invention, contactor holder plates 114 and118 may be separated by dielectric layer 116—for example and withoutlimitation, dielectric layer 116 may be present in regions whichsurround those of the contactors that carry signals (for example,contactors 110 ₂, 110 ₄ and 110 _(n) shown in FIG. 2A). In accordancewith one or more such embodiments of the present invention, dielectriclayer 116 may be used to space contactor holder plates 114 and 118 toadjust a characteristic impedance of certain contactors to apredetermined value, for example and without limitation, fifty (50) ohmswhere the characteristic impedance of the certain contactors may bedetermined by, among other things, the thickness and material propertiesof contactor holder plates 114 and 118, the diameter of through holesfor the certain contactors, the barrel body diameter of the certaincontactors, the dielectric constant(s) of dielectric material(s) in thethrough hole, and the thickness and dielectric constant of dielectricsheet 116, if present, (where dielectric sheet 116 may comprise one ormore dielectric sheets of the same or differing dielectric constants)—asmay be calculated using any one of a number of three dimensional fieldsolver algorithms (for example, the IBM Electromagnetic Field SolverSuite of Tools) that are well known to those of ordinary skill in theart.

As further shown in FIG. 2A, and in accordance with one or moreembodiments of the present invention, contactor holder plates 114 and118 are thermally connected to air-cooled, finned heat sink 138. Inaccordance with one or more such embodiments, heat sink 138 is made of athermally conductive material such as, for example and withoutlimitation, copper, aluminum alloy 6061, or copper alloy 145, all ofwhich are commonly available. In addition, in accordance with one ormore such embodiments, heat sink 138 may be integral with one or both ofcontactor holder plates 114 and 118.

In addition, and in accordance with one or more embodiments of thepresent invention, contactors 110 ₁-110 _(n) may be arranged in apattern of impedance-controlled signal contactors and low impedancepower and ground contactors that matches that of terminals and contactsto which socket 100 may be connected. In further addition, as shown inFIG. 2B, and in accordance with one or more embodiments of the presentinvention, socket 100 may be connected to a DUT board by means of, forexample and without limitation, cap head screws (not shown), located infour counter-bored holes 135 ₁-135 ₄ in the corners of socket 100.

As shown in FIG. 2A, and in accordance with one or more embodiments ofthe present invention, contactor holder plates 114 and 118 have throughholes 120 ₁, 120 ₃, and 120 ₅ of diameter D₁ and through holes 120 ₂,120 ₄, and 120 ₆ of diameter D₂; wherein D₁ and D₂ are different andD₂>D₁. In addition, as further shown in FIG. 2A, each of contactors 110₁-110 _(n) has a body with substantially the same diameter. As such,there is a different spacing between the barrel bodies of certain onesof contactors 110 ₁-110 _(n) and their corresponding through holes. As aresult, and in accordance with the present invention, this provides adifference in impedance of, and thermal resistance to, contactor holderplates 114 and 118 for certain ones of contactors 110 ₁-110 _(n).

As further shown in FIG. 2A, each of contactors 110 ₁-110 _(n) isseparated from contactor holder plates 114 and 118 by an air gap. Inaccordance with one or more further such embodiments of the presentinvention, to further avoid contact between contactors 110 ₁-110 _(n)and contactor holder plates 114 and 118, an inside surface of eachthrough hole in contactor holder plates 114 and 118 may be coated with athin dielectric layer such as, for example and without limitation,Parylene. In accordance with one or more such embodiments, a dielectriclayer may extend over all or portions of other surfaces of the contactorholder plate(s).

In accordance with one or more embodiments of the present invention,contactors 110 ₁, 110 ₃, and 110 ₅ (having a relatively small spacebetween a side of corresponding through holes and a barrel body of thesecontactors) may be used to contact power or ground terminals of adevice, and contactors 110 ₂, 110 ₄, and 110 _(n) (having a relativelylarger space between a side of corresponding through holes and a barrelbody of these contactors) may be used to contact signal terminals of thedevice.

In accordance with one or more embodiments of the present invention,benefits may be achieved for socket 100 by having a spacing between thebarrel body of each contactor used to contact power or ground terminalsof a device and a surface of their through holes in contactor holderplates 114 and 118 that is small. Preferably, a small spacing of about0.1 mm provides a relatively low thermal resistance between contactorsused to contact power or ground terminals and thermally conductivecontactor holder plates 114 and/or 118 (when compared with a thermalresistance between contactors used to contact signal terminals andcontactor holder plates 114 and 118). Advantageously, this results in anenhanced thermal conductivity from power and ground contactors tocontactor holder plates 114 and 118. Thus, in accordance with theenhanced thermal conductivity provided by socket 100, the amount ofcurrent carried by power and ground contactors can be increased.

As one can readily appreciate from FIG. 2A, heat is conducted: (a)through the spacing between each contactor and its corresponding throughhole in contactor holder plates 114 and 118 and away from the contactor;(b) through contactor holder plates 114 and/or 118; and (c) intoair-cooled, finned heat sink 138 (refer to FIG. 2B). Also, in accordancewith one or more such embodiments, thermal conductivity from a contactor(used to contact power or ground terminals) to contactor holder plates114 and 118 is high due to a small spacing between a barrel body of thecontactor probe and a corresponding through hole in contactor holderplates 114 and 118. As one of ordinary skill in the art can readilyappreciate, socket 10 described above in conjunction with FIG. 1A, mayalso use an air-cooled, finned heat sink like heat sink 138 instead ofheat sink 38. In addition, as one of ordinary skill in the art canreadily appreciate, socket 10 described above in conjunction with FIG.1A and socket 100 described above in conjunction with FIGS. 2A and 2Bmay also a fluid cooled cold plate, a convection cooled cold plate, andother heat sinks known in the art instead of heat sink 38 and heat sink138, respectively.

In accordance with one or more embodiments of the present invention,contactor holder plates 114 and/or 118 may be electrically conductivemetallic plates. Further, certain of the contactors may be used tocontact signal terminals on a device. Typically, signal connectionsthrough a socket are designed to have an electrical impedance between 20and 100 ohms, and preferably 50 ohms. To estimate signal contactorelectrical impedance, one may use a ratio of a diameter of a throughhole in contactor holder plates 114 and 118 to an average diameter of abarrel body of such contactors used to contact signal terminals disposedin the through hole—taken together with a design of such contactors (forexample, a shape of the barrel body of such contactors, and electricalproperties of such contactors), spacing to nearest neighbor contactors,and effects of various dielectric layers such as dielectric layer 116.In applications where air fills the space in the through holes and thethickness of dielectric layer 116 is negligible with respect to thethickness of metallic contactor holder plates 114 and 118, the impedanceof a contactor used for signal terminals is given approximately byZ_(S)=60 ln(D_(signal hole)/D_(signal body)). As such, in accordancewith one or more embodiments of the present invention, for applicationswhere air fills the space, the diameter of a cylindrical, coaxialthrough hole (D_(signal hole)) in contactor holder plates 114 and 118(when configured as a ground shield) is about 2.3 times the diameter ofthe barrel body (D_(signal body)) of contactors used to contact signalterminals to achieve a signal impedance of 50 ohms.

Further advantages accrue for embodiments wherein contactor holderplates 114 and/or 118 are metallic due to a reduction of impedance ofthe power and ground spring probes. As is well known to those ofordinary skill in the art, a low impedance contactor is advantageous formaking power and ground connections to a high performance device toreduce noise at the power and ground in the device caused byfluctuations in power and ground currents.

To estimate power or ground contactor impedance, one may use a ratio ofa diameter of a through hole in contactor holder plates 114 and 118 toan average diameter of a barrel body of contactors used to contact poweror ground terminals disposed in the through hole—taken together with adesign of such contactors (for example, a shape of the barrel body ofsuch contactors, and electrical properties of such contactors), spacingto nearest neighbor contactors, and effects of various dielectric layerssuch as dielectric layer 116. In applications where air fills the spacein the through holes and contactor holder plates 114 and 118 aremetallic, the impedance of a contactor used for power or groundterminals is given approximately by Z_(P)=60ln(D_(power hole)/D_(power body)). In this approximation, D_(power hole)is the diameter of the power or ground through hole in contactor holderplates 114 and 118, and D_(power body) is the average diameter of thebody of the power or ground contactor. As such, and in accordance withone or more embodiments of the present invention, the impedance of powerand ground contactors is preferably no more than 80 percent of theimpedance of signal contactors to provide a significant reduction inpower and ground characteristic impedance. In accordance withmathematical formulations for impedance, a requirement that the powercontactor characteristic impedance be 80 percent or less than the signalcontactor characteristic impedance is approximately satisfied by amathematical expression:(D_(signal hole)/D_(signal body))≈1.18*(D_(power hole)/D_(power body)).Equivalently, the requirement that the power contactor impedance be nogreater than 80 percent of the signal contactor impedance isapproximately satisfied by a second mathematical expression:(A_(signal hole)/A_(signal body))≈1.4*(A_(power hole)/A_(power body)).In this second mathematical expression,(A_(signal hole)/A_(signal body)) is a ratio of the cross sectional areaof the through hole for the signal contactor to the cross sectional areaof the body of the signal contactor. Correspondingly,A_(power hole)/A_(power body)) is a ratio of the cross sectional area ofthe through hole for the power or ground contactor to the crosssectional area of the body of the power or ground contactor. Further,for embodiments in which any of the through holes in the holder platesor any of the contactor bodies is not a right circular cylinder, thesecond mathematical expression is an approximate estimation of therequirement necessary to provide that a power and ground contactor has acharacteristic impedance that is 80 percent or less than thecharacteristic impedance of a signal contactor.

As one can readily appreciate from the above, one or more embodiments ofsocket 100 that incorporate electrically conductive (for example,metallic) contactor holder plates may provide: (a) well shielded,controlled impedance, contactors for signal terminals (for example animpedance of about 50 ohms); (b) low impedance power or groundcontactors; and (c) a thermal conduction path from power or groundcontactors to a heat sink. In addition, the controlled impedancetogether with electrical shielding of adjacent contactors by conductivecontactor holder plates 114 and 118, provides a high integrity signalpath for high performance devices.

In accordance with one or more embodiments of the present invention,contactors 110 ₁-110 _(n) are spring probes of type B1679-K10 (availablefrom Rika Denshi) that have a barrel body diameter (D_(C)) of about 0.35mm. Further, in accordance with one or more such embodiments, thecontactors used to contact signal terminals are disposed in throughholes having a diameter D₂ of about 0.78 mm, and the contactors used tocontact power or ground terminals are disposed in through holes having adiameter D₁ of about 0.40 mm. Still further, in accordance with one ormore such embodiments, a grid spacing between contactors is about 1.0mm, and dielectric sheets 120 and 122 are thin sheets of dielectricmaterial, for example and without limitation, each may be a film ofpolyimide flex materials having a thickness of about 0.05 mm. Stillfurther, in accordance with one or more such embodiments, dielectriclayer 116 is a polyimide sheet having a thickness of about 0.1 mm. Yetstill further, in accordance with one or more such embodiments,contactor holder plates 114 and 118 are anodized aluminum plates.Advantageously, in accordance with such embodiments, an anodizedaluminum layer in the through holes of contactor holder plates 114 and118 prevents contactors 110 ₁-110 _(n) from making electrical contactwith contactor holder plates 114 and 118. In further addition, anelectrical impedance of a contactor used to contact power and groundterminals, for the design details set forth above, is about 8 ohms. Asone of ordinary skill in the art can readily appreciate, socket 10described above in conjunction with FIG. 1A, may also use anodizedaluminum plates for contactor holder plates 14 and 18. Further, inaccordance with one or more embodiments of the present invention,contactor holder plates may be conformally coated with a film ofinsulating material by means well known to those of ordinary skill inthe art such as, for example and without limitation, chemical vapordeposition, immersion coating, electrodeposition coating, and thermaldecomposition coating.

Although the above-described embodiments used contactors of the Pogo®spring contact type, it should be understood by one of ordinary skill inthe art that this does not limit all embodiments of the presentinvention to their use. In fact, further embodiments of the presentinvention may be fabricated wherein other contactors are used such as,for example and without limitation, barrel springs available fromMill-Max Manufacturing Corp. of Oyster Bay, N.Y., contact springs,formed springs, and tubular connectors. It should be further understoodby one of ordinary skill in the art that spring probes of many shapesand specifications may be used in place of the above-described EverettCharles spring probes. Lastly, it should be understood by one ofordinary skill in the art that the spring probes shown in FIG. 2A arerepresentations that are provided for purposes of simplifying theexplanation of the embodiment, and that they are not an exactrepresentation of any particular spring probe.

Thus, as was set forth above, for the embodiments shown in FIGS. 1A and2A, a first ratio of a diameter of a through hole for contactors used tocontact signal terminals to a diameter of a barrel body of contactorsused to contact signal terminals that are disposed in the through holeought to be about the same, namely, about 2.3. Similarly, for theembodiments shown in FIGS. 1A and 2A, a second ratio of a diameter of athrough hole for contactors used to contact power or ground terminals toa diameter of a barrel body of contactors used to contact power orground terminals that are disposed in the through hole ought to be aboutthe same, and the second ratio should preferably be less than the firstratio. In accordance with one or more such embodiments, the second ratio(i.e., for power and ground contactors) is no greater than 0.8 times thefirst ratio (for signal contactors).

However, as one of ordinary skill in the art can readily appreciate,further embodiments of the present invention exist wherein through holesare varied in size, and wherein the size of the bodies of contactors arevaried in size. Further, the ratios of a diameter of a through hole forcontactors to a diameter of a contactor body that is disposed in thethrough hole may be about the same as those set forth above for thevarious functions to be served by the specific contactor.

As one of ordinary skill in the art can readily appreciate, inaccordance with one or more further embodiments of the presentinvention, thin dielectric sleeves may be inserted in through holes inthe contactor holder plates (for example and without limitation, byinsertion into opposite ends of a through hole) to abut against thesides of the through hole—the thickness of the dielectric sleeve oughtto be such that it does not significantly change a desired contactorimpedance (for example, in accordance with one or more embodiments, thedielectric sleeve does not contact a contactor body), or if it does not,other parameters discussed herein may have to be adjusted in the mannerdiscussed herein to achieve the desired contactor impedance. Inaddition, in accordance with one or more such embodiments, dielectricsleeves may be inserted into opposite ends of each through hole, to abutagainst a conductive ring of a Pogo® spring contact that has beeninserted into the through hole, and thereby, hold the Pogo® springcontact in place vertically. Further, and in accordance with one or moresuch embodiments, a contact lubricant (for example and withoutlimitation, a thermally conductive lubricant) or other dielectric fluidmay be applied to the space between tube connectors and correspondingholes in the contactor holder plates.

FIGS. 3A and 3B show a cross sectional view and a top view,respectively, of socket 200 that is fabricated in accordance with one ormore still further embodiments of the present invention—FIG. 3A is across sectional view of socket 200 in a direction indicated by arrowsAA′ in FIG. 3B. In accordance with one or more embodiments of thepresent invention, socket 200 can be used, among other things, as asocket for contacting an integrated circuit or other microelectronic orelectronic device.

As shown in FIG. 3A, socket 200 comprises contactors in the form oftubular connectors 210 ₁-210 _(n) that are held in circular, cylindricalthrough holes in contactor holder plate 214 by dielectric sheet 216. Inaccordance with one or more such embodiments of the present invention,dielectric layer 216 may be used to adjust a characteristic impedance ofcertain contactors to a predetermined value, for example and withoutlimitation, fifty (50) ohms where the characteristic impedance of thecertain contactors may be determined by, among other things, thethickness and material properties of contactor holder plate 214, thediameter of through holes for the certain contactors, the tube bodydiameter of the certain contactors, the dielectric constant(s) ofdielectric material(s) in the through hole, and the thickness anddielectric constant of dielectric sheet 216 (where dielectric sheet 216may comprise one or more dielectric sheets of the same or differingdielectric constants)—as may be calculated using any one of a number ofthree dimensional field solver algorithms (for example, the IBMElectromagnetic Field Solver Suite of Tools) that are well known tothose of ordinary skill in the art. In addition, dielectric sheet 216prevents tubular connectors 210 ₁-210 _(n) from making contact withcontactor holder plate 214.

In accordance with one or more such embodiments of the presentinvention, contactor holder plate 214 is a thermally conductive platehaving through holes that accommodate tubular connectors 210 ₁-210 _(n).In accordance with one or more such embodiments of the presentinvention, contactor holder plate 214 is made of a thermally conductivematerial such as, for example and without limitation, copper, copperalloys (for example and without limitation, copper alloy 145 that isavailable from Olin Corporation of Norwalk, Conn.), bronze, copperplated, nickel-iron alloys (for example and without limitation, copperplated invar), silver alloys, aluminum, aluminum alloys, berylia,aluminum nitride, silicon, and silicon carbide. In accordance with oneor more such embodiments, the material used to fabricate contactorholder plate 214 is selected to have a relatively high thermalconductivity, for example and without limitation, 0.1 Watts/° C.-cm² orgreater and preferably greater than 0.3 Watts/° C.-cm². Further, inaccordance with one or more further such embodiments, as shown in FIG.3A, contactor holder plate 214 has substantially parallel, planar majortop and bottom surfaces, and top and bottom ends of tubular connector210 ₁-210 _(n) are substantially flush with the top and bottom surfacesof contactor holder plate 214. One of ordinary skill in the art willreadily appreciate that further embodiments exist wherein the top and/orbottom ends of tubular connectors 210 ₁-210 _(n) may extend beyond thetop and bottom surfaces of contactor holder plate 214 while providingthat power and/or ground contactors have a higher thermal conductivityto the contactor holder plate(s) than signal contactors have.

In accordance with one or more such embodiments, each of tubularconnectors 210 ₁-210 _(n) comprises an electrically conductive tubehaving slots through the tube at each end that extend longitudinallyalong the tube axis a predetermined distance away from each end (referto FIGS. 4C and 4D). Further, in accordance with one or more suchembodiments, a predetermined number of such slots are disposed about thetube circumference in a configuration that provides a slotted springuseful to engage contacts and/or terminals to which socket 200 may beconnected. The number of slots, the disposition of slots about thecircumference of a tube, and the length of the slots at each end of thetube may be determined routinely and without undue experimentation byone of ordinary skill in the art to provide a desired force required forconnection to, and retention thereof at, a terminal and/or a contact.

As further shown in FIG. 3A, and in accordance with one or moreembodiments of the present invention, contactor holder plate 214 isthermally connected to air-cooled, finned heat sink 238. In accordancewith one or more such embodiments, heat sink 238 is made of a thermallyconductive material such as, for example and without limitation, copper,aluminum alloy 6061, carbon fiber filled polymer, or copper alloy 145,all of which are commonly available. In addition, in accordance with oneor more such embodiments, heat sink 238 may be integral with contactorholder plate 214.

In addition, and in accordance with one or more embodiments of thepresent invention, tubular contactors 210 ₁-210 _(n) may be arranged ina pattern of impedance-controlled signal contactors and low impedancepower and ground contactors that matches that of terminals and contactsto which socket 200 may be connected. In further addition, as shown inFIG. 3B, and in accordance with one or more embodiments of the presentinvention, socket 200 may be attached to a DUT board by means of, forexample and without limitation, cap head screws (not shown) located infour counter-bored holes 235 ₁-235 ₄ in the corners of socket 200.

As shown in FIG. 3A, and in accordance with one or more embodiments ofthe present invention, contactor holder plate 214 has through holes 220₁, 220 ₃, and 220 ₅ of diameter D₁ and through holes 220 ₂, 220 ₄, and220 _(n) of diameter D₂; wherein D₁ and D₂ are different and D₁>D₂. Inaddition, as further shown in FIG. 3A, each of tube connectors 210 ₁-210_(n) has a body with substantially the same outside diameter. As such,there is a different spacing between the tube bodies of certain ones oftube connectors 210 ₁-210 _(n) and their corresponding through holes. Asa result, and in accordance with the present invention, this provides adifference in impedance of, and thermal resistance to, contactor holderplate 214 for, certain ones of tube connectors 210 ₁-210 _(n).

As further shown in FIG. 3A, each of tube connectors 210 ₁-210 _(n) isseparated from contactor holder plate 214 by an air gap. In accordancewith one or more further such embodiments of the present invention, tofurther avoid contact between tube connectors 210 ₁-210 _(n) andcontactor holder plate 214, an inside surface of each through hole incontactor holder plate 214 may be coated with a thin dielectric layersuch as, for example and without limitation, Parylene. In accordancewith one or more such embodiments, a dielectric layer may extend overall or portions of other surfaces of the contactor holder plate(s).

In accordance with one or more embodiments of the present invention,tube connectors 210 ₂, 210 ₄, and 210 _(n) (having a relatively smallspace between a side of corresponding through holes and a tube body ofthese tube connectors) may be used to contact power or ground terminalsof a device, and tube connectors 210 ₁, 210 ₃, and 210 ₅ (having arelatively larger space between a side of corresponding through holesand a tube body of these tube connectors) may be used to contact signalterminals of the device.

In accordance with one or more embodiments of the present invention,benefits may be achieved for socket 200 by having a spacing between thetube body of each contactor used to contact power or ground terminals ofa device and a surface of their through holes in contactor holder plate214 that is small. Preferably, a small spacing of about 0.1 mm providesa relatively low thermal resistance between contactors used to contactpower or ground terminals and thermally conductive contactor holderplate 214 (when compared with a thermal resistance between contactorsused to contact signal terminals and contactor holder plate 214).Advantageously, this results in an enhanced thermal conductivity frompower and ground contactors to contactor holder plate 214. Thus, inaccordance with the enhanced thermal conductivity provided by socket200, the amount of current carried by power and ground contactors can beincreased.

As one can readily appreciate from FIG. 3A, heat is conducted: (a)through the spacing between each tube connector and its correspondingthrough hole in contactor holder plate 214 and away from the tubeconnector; (b) through contactor holder plate 214; and (c) intoair-cooled, finned heat sink 238 (refer to FIG. 3B). Also, in accordancewith one or more such embodiments, thermal conductivity from a tubeconnector (used to contact power or ground terminals) to contactorholder plate 214 is high due to a small spacing between a tube body ofthe tube connector and a corresponding through hole in contactor holderplate 214. As one of ordinary skill in the art can readily appreciate,socket 200 described above in conjunction with FIG. 3A, may also use afluid cooled cold plate, a convection cooled cold plate, and other heatsinks known in the art instead of heat sink 238.

In accordance with one or more embodiments of the present invention,contactor holder plate 214 may be an electrically conductive metallicplate. Further, certain of the contactors may be used to contact signalterminals on a device. Typically, signal connections through a socketare designed to have an electrical impedance between 20 and 100 ohms,and preferably 50 ohms. To estimate signal contactor electricalimpedance, one may use a ratio of a diameter of a through hole incontactor holder plate 214 to an average diameter of a tube body of suchcontactors used to contact signal terminals disposed in the throughhole—taken together with a design of such contactors (for example, ashape of the tube body of such contactors, and electrical properties ofsuch contactors), spacing to nearest neighbor contactors, and effects ofvarious dielectric layers such as dielectric layer 216. In applicationswhere air fills the space in the through holes and the thickness ofdielectric layer 216 is negligible with respect to the thickness ofmetallic contactor holder plate 214, the impedance of a contactor usedfor signal terminals is given approximately by Z_(S)=60ln(D_(signal hole)/D_(signal body)). As such, in accordance with one ormore embodiments of the present invention, for applications where airfills the space, the diameter of a cylindrical, coaxial through hole(D_(signal hole)) in contactor holder plate 214 (when configured as aground shield) is about 2.3 times the diameter of the tube body(D_(signal body)) of contactors used to contact signal terminals toachieve a signal impedance of 50 ohms.

Further advantages accrue for embodiments wherein contactor holder plate214 is metallic due to a reduction of impedance of the power and groundspring probes. As is well known to those of ordinary skill in the art, alow impedance contactor is advantageous for making power and groundconnections to a high performance device to reduce noise at the powerand ground in the device caused by fluctuations in power and groundcurrents.

To estimate power or ground contactor impedance, one may use a ratio ofa diameter of a through hole in contactor holder plate 214 to an averagediameter of a tube body of contactors used to contact power or groundterminals disposed in the through hole—taken together with a design ofsuch contactors (for example, a shape of the tube body of suchcontactors, and electrical properties of such contactors), spacing tonearest neighbor contactors, and effects of various dielectric layerssuch as dielectric layer 216. In applications where air fills the spacein the through holes and contactor holder plate 214 is metallic, theimpedance of a contactor used for power or ground terminals is givenapproximately by Z_(P)=60 ln(D_(power hole)/D_(power body)). In thisapproximation, D_(power hole) is the diameter of the power or groundthrough hole in contactor holder plate 214, and D_(power body) is theaverage diameter of the body of the power or ground contactor. As such,and in accordance with one or more embodiments of the present invention,the impedance of power and ground contactors is preferably no more than80 percent of the impedance of signal contactors to provide asignificant reduction in power and ground characteristic impedance. Inaccordance with mathematical formulations for impedance, a requirementthat the power contactor characteristic impedance be 80 percent or lessthan the signal contactor characteristic impedance is approximatelysatisfied by a mathematical expression:(D_(signal hole)/D_(signal body))≈1.18*(D_(power hole)/D_(power body)).Equivalently, the requirement that the power contactor impedance be nogreater than 80 percent of the signal contactor impedance isapproximately satisfied by a second mathematical expression:(A_(signal hole)/A_(signal body))≈1.4*(A_(power hole)/A_(power body)).In this second mathematical expression,(A_(signal hole)/A_(signal body)) is a ratio of the cross sectional areaof the through hole for the signal contactor to the cross sectional areaof the body of the signal contactor. Correspondingly,A_(power hole)/A_(power body)) is a ratio of the cross sectional area ofthe through hole for the power or ground contactor to the crosssectional area of the body of the power or ground contactor. Further,for embodiments in which any of the through holes in the holder platesor any of the contactor bodies is not a right circular cylinder, thesecond mathematical expression is an approximate estimation of therequirement necessary to provide that a power and ground contactor has acharacteristic impedance that is 80 percent or less than thecharacteristic impedance of a signal contactor.

As one can readily appreciate from the above, one or more embodiments ofsocket 200 that incorporate electrically conductive (for example,metallic) contactor holder plates may provide: (a) well shielded,controlled impedance, contactors for signal terminals (for example animpedance of about 50 ohms); (b) low impedance power or groundcontactors; and (c) a thermal conduction path from power or groundcontactors to a heat sink. In addition, the controlled impedancetogether with electrical shielding of adjacent contactors by conductivecontactor holder plate 214, provides a high integrity signal path forhigh performance devices.

In accordance with one or more embodiments of the present invention,tubular connectors 210 ₁-210 _(n), are fabricated from electricallyconductive metal such as, for example and without limitation, copper,beryllium copper alloys (for example and without limitation, copperalloy 194 that is available from Olin Corporation of Norwalk, Conn.),silver alloys, or stainless steel alloys, and have, for example andwithout limitation, an inner diameter (“ID”) of about 0.45 mm and anouter diameter (“OD”) of about 0.55 mm. Further, in accordance with oneor more such embodiments, the tube connectors used to contact signalterminals are disposed in through holes having a diameter D₁ of about1.2 mm, and the tube connectors used to contact power or groundterminals are disposed in through holes having a diameter D₂ of about0.65 mm. Still further, in accordance with one or more such embodiments,a grid spacing between contactors is about 1.27 mm. Still further, inaccordance with one or more such embodiments, dielectric layer 216 is apolyimide sheet having a thickness of about 50 microns. Yet stillfurther, in accordance with one or more such embodiments, contactorholder plate 214 is an anodized aluminum plate. Advantageously, inaccordance with such embodiments, the anodized aluminum layer in thethrough holes of contactor holder plate 214 prevents tube connectors 210₁-210 _(n) from making electrical contact with contactor holder plate214. Further, in accordance with one or more embodiments of the presentinvention, contactor holder plates may be conformally coated with a filmof insulating material by means well known to those of ordinary skill inthe art such as, for example and without limitation, chemical vapordeposition, immersion coating, electrodeposition coating, and thermaldecomposition coating.

As one of ordinary skill in the art can readily appreciate, furtherembodiments of the present invention exist wherein through holes arevaried in size, and wherein the size of the bodies of tubes are variedin size.

As one of ordinary skill in the art can readily appreciate, inaccordance with one or more further embodiments of the presentinvention, thin dielectric sleeves may be inserted in the through holesin the contactor holder plate (for example and without limitation, byinsertion into opposite ends of each through hole) to abut against thesides of the through hole—the thickness of the dielectric sleeve oughtto be such that it does not significantly change a desired tubeconnector impedance (for example, in accordance with one or moreembodiments, the dielectric sleeve does not contact a connector body),or if it does not, other parameters discussed herein may have to beadjusted in the manner discussed herein to achieve the desired contactorimpedance. In addition, in accordance with one or more such embodiments,dielectric sleeves may be inserted into opposite ends of each throughhole, to abut against a conductive ring of a tube connector that hasbeen inserted into the through hole, and thereby, hold the tubeconnector in place vertically. Further, and in accordance with one ormore such embodiments, a contact lubricant (for example and withoutlimitation, a thermally conductive lubricant) or other dielectric fluidmay be applied to the space between tube connectors and correspondingholes in the contactor holder plate or plates.

In accordance with one or more embodiments of the present invention, acontactor may have protuberances disposed on a surface of the contactorbody that is disposed in a through hole of a contactor holder plate(s).Such protuberances may be in the form of ribs that are useful in holdingthe contactor by, for example and without limitation, placing dielectricinserts in a through hole above and/or below the protuberance(s). Inaccordance with one or more such embodiments, the protuberances occupyless than ten (10) percent of the surface area of the contactor bodydisposed in a through hole.

In accordance with one or more embodiments of the present invention, across section of a through hole may be: (a) circular (or substantiallycircular depending on fabrication tolerances) to form a cylindricalthrough hole; (b) polygonal; or (c) any other desired shape. Likewise,in accordance with one or more embodiments of the present invention, across section of a contactor body disposed in a through hole may have asimilar variety of shapes. In such cases, the characteristic impedanceof a contactor placed in a through hole may be determined by, amongother things, the thickness and material properties of contactor holderplate(s), the cross sectional area of the through hole (for circular orsubstantially circular cross sections, a diameter may serve as a proxyfor the cross sectional area), the cross sectional area of the body ofthe contactor (for circular or substantially circular body crosssections, a diameter may serve as a proxy for the cross sectional area),the dielectric constant(s) of dielectric material(s) in the throughhole, and the thickness and dielectric constant of dielectric sheet(s),if present—as may be calculated using any one of a number of threedimensional field solver algorithms (for example, the IBMElectromagnetic Field Solver Suite of Tools) that are well known tothose of ordinary skill in the art. In performing such a calculation,for a through hole having an arbitrary cross section, one may use anaverage cross sectional area of the through hole, where, for example andwithout limitation, the average cross sectional area is an average ofthe cross sectional area of one or more like-sized through holesaveraged, for example and without limitation, over a length of thethrough holes. Thus, for a through hole having a circular orsubstantially circular cross section, one may use an average diameter ofa cross section of the through hole where the average diameter is anaverage of the diameter for one or more like-sized through holesaveraged, for example, over a length of the through holes. Further, inperforming such a calculation, for a contactor body having an arbitrarycross section, one may use a maximum cross sectional area of thecontactor body, where the maximum cross sectional area excludes anyprotuberances extending from the contactor body, where suchprotuberances, for example, occupy less than ten (10) percent of thesurface area of the contactor body disposed in the through hole. Thus,for a contactor body having a circular or substantially circular crosssection, one may use a maximum diameter of the contactor body where themaximum diameter excludes any protuberances extending from the contactorbody, where such protuberances, for example, occupy less than ten (10)percent of the surface area of the contactor body. Alternatively, for acontactor body having an arbitrary cross section, one may use an averagecross sectional area of the contactor body where the average crosssectional area excludes any protuberances extending from the contactorbody, where such protuberances, for example, occupy less than ten (10)percent of the surface area of the contactor body. Thus, for a contactorbody having a circular or substantially circular cross section, one mayuse a average diameter of the contactor body where the average diameterexcludes any protuberances extending from the contactor body, where suchprotuberances, for example, occupy less than ten (10) percent of thesurface area of the contactor body.

In accordance with one or more embodiments of the present invention,contactor holder plates 14 and 18, contactor holder plates 114 and 118,and contactor holder plate 214 may comprise a single sheet (for example,a metallic sheet) or they may be built by stacking layers of thin sheets(for example, metallic sheets) with through holes disposed in an arrayand aligned to accommodate contactors in the respective through holes.In accordance with one or more such embodiments, contactor holder platesmay be made, for example and without limitation, of about 60 micronthick sheets of copper alloy 110 in which an array of through holes isetched by lithographic methods that are well known to those of ordinaryskill in the art. In addition, in accordance with one or more furthersuch embodiments, the thin sheets (for example, metallic sheets) may bespaced apart to allow air or other cooling fluid to pass therebetweenand to conduct heat away from contactors held in a contactor holderplate comprised of a stack of sheets (for example, metallic sheets). Inaccordance with one or more such embodiments, if comprised of thin metalsheets, one or more of them may be coated with a thin dielectric layer(wherein such a dielectric layer may extend over all or portions ofsurfaces of the contactor holder plate(s)) to prevent electrical contactbetween the metal sheets and contactors inserted in through holesthrough the stack of sheets.

In accordance with one or more embodiments of the present invention,contactor holder plates may comprise one or more electrically conductivelayers and one or more thermally conductive layers. In accordance withone or more such embodiments, electrically conductive layers maycomprise a metal such as, for example and without limitation, copper,beryllium-copper, copper alloys, copper plated invar, silver alloys,aluminum, aluminum alloys, and carbon fiber filled polymer. In addition,and in accordance with one or more such embodiments, thermallyconductive layers may comprise alumina, aluminum nitride, silicon,silicon carbide and/or a layer having a thermal conductivity of 0.1Watts/° C.-cm² or greater.

In accordance with one or more embodiments of the present invention, asshown in FIGS. 2B and 3B, heat sinks 138 and 238, respectively, havefins. In accordance with one or more such embodiments, the fins mayinclude surface protrusions such as, for example and without limitation,an array of pins, and cooling is provided by a flow of air over the finsand surface protrusions. Such an air flow may occur by convective flow.

FIG. 4A shows a partial sectional view of socket 400 that is fabricatedin accordance with one or more embodiments of the present inventionwherein signal and power/ground contactors comprise spring probes suchas signal spring probe 402 ₁ and power/ground spring probe 402 ₂,respectively. As shown in FIG. 4A, the spring probes are held in throughholes in contactor holder plate 408 by dielectric sheets 406 and 412(for example and without limitation, thin sheets of polyimide) havingholes for spring pins of spring probes 402 ₁ and 402 ₂. In accordancewith one or more embodiments of the present invention, contactor holderplate 408 is thermally conductive, and in accordance with one or morefurther embodiments of the present invention, contactor holder plate 408is electrically conductive. Lastly, as shown in FIG. 4A, and inaccordance with one or more embodiments of the present invention,contactor holder plate 408 is in good thermal contact with thermallyconductive holder bracket 414.

FIG. 4B shows a partial sectional view of socket 420 that is fabricatedin accordance with one or more embodiments of the present inventionwherein signal and power/ground contactors comprise spring probes suchas signal spring probe 424 and power/ground spring probe 422,respectively. As shown in FIG. 4B, power and ground spring probes 422and signal spring probes 424 are held in the centers of through holes436 ₁-436 ₄ and 434 ₁-434 ₄, respectively, in a stack of contactorholder plates 426 ₁-426 ₄ by holes in thin dielectric sheets 428 and 432(labels for through holes 436 ₂-436 ₄ and through holes 434 ₂-434 ₄ areomitted from FIG. 4B for clarity of illustration). In accordance withone or more embodiments of the present invention, one or more ofcontactor holder plates 426 ₁-426 ₄ are thermally conductive, and inaccordance with one or more further embodiments of the presentinvention, one or more of contactor holder plates 426 ₁-426 ₄ areelectrically conductive. In accordance with one or more such furtherembodiments of the present invention, one or more of contactor holderplates 426 ₁-426 ₄ may be insulated, for example and without limitation,with a thin dielectric coating to prevent electrical shorts to springprobes 422 and 424. In accordance with one or more such furtherembodiments, the dielectric coating may extend over all or portions ofsurfaces of the contactor holder plate(s). In accordance with one ormore such further embodiments, the insulation for each of contactorholder plates 426 ₁-426 ₄ may be provided by a layer of anodizedaluminum.

As still further shown in FIG. 4B, and in accordance with one or moreembodiments of the present invention, contactor holder plates 426 ₁-426₄ are stacked and have a spacing between them at thinned sections in aregion disposed about through holes 434 ₁-434 ₄ that is designed toachieve a characteristic impedance of about fifty (50) ohms for signalspring probe 424. Thus, in accordance with one or more such embodiments,the thickness of contactor holder plates 426 ₁-426 ₄ about certaincontactors may be different than it is about other contactors to adjustthe impedance of certain contactors. In addition, a diameter of throughholes 436 ₁-436 ₄ for spring probe 422 is smaller than 2.3 times the ODof tube connector 422, as might be the case for certain embodimentswherein a through hole exists in a solid contactor holder plate(s),i.e., a configuration of contactor holder plate(s) not having spacingbetween contactor holder plates shown in FIG. 4B. In further addition,and in accordance with one or more such embodiments of the presentinvention, the spacing between contactor holder plates 426 ₁-426 ₄ canbe filled with air, dielectric coatings on the plates, or by adielectric layer. In accordance with one or more such embodiments, thedielectric coating or layer may extend over all or portions of surfacesof the contactor holder plate(s). Lastly, in accordance with one or moreembodiments of the present invention, and as shown in FIG. 4B, channels456 ₁-456 ₄ in contactor holder plates 426 ₁-426 ₄ may be used tocirculate a thermal transfer fluid injected into the channels through anaperture (not shown).

FIG. 4C shows a partial sectional view of socket 440 that is fabricatedin accordance with one or more embodiments of the present inventionwherein signal and power/ground contactors comprise tubular connectorssuch as signal tubular connector 444 and power/ground tubular connector442, respectively. As shown in FIG. 4C, tubular connectors 442 and 444are held in the centers of through holes in a stack of contactor holderplates 446 ₁-446 ₄ by dielectric sheet 448. In accordance with one ormore embodiments of the present invention, one or more of contactorholder plates 446 ₁-446 ₄ are thermally conductive, and in accordancewith one or more further embodiments of the present invention, one ormore of contactor holder plates 426 ₁-426 ₄ are electrically conductive.As further shown in FIG. 4C, and in accordance with one or more suchfurther embodiments of the present invention, contactor holder plates446 ₁-446 ₄ are insulated by a thin dielectric coating to preventelectrical shorts to tubular connectors 442 and 444. In accordance withone or more such further embodiments, the dielectric coating may extendover all or portions of surfaces of the contactor holder plate(s). Inaccordance with one or more such further embodiments, the insulation foreach of contactor holder plates 446 ₁-446 ₄ may be provided by a thin,conformal layer of anodized aluminum.

As still further shown in FIG. 4C, and in accordance with one or more 30embodiments of the present invention, contactor holder plates 446 ₁-446₄ are stacked and have a spacing between them that is designed toachieve a characteristic impedance of about fifty (50) ohms for tubeconnector 444. In addition, a diameter of through holes for tubeconnector 442 is smaller than 2.3 times the OD of tube connector 442, asmight be the case for certain embodiments wherein a through hole existsin a solid contactor holder plate(s).

FIG. 4D shows a partial sectional view of socket 460 that is fabricatedin accordance with one or more embodiments of the present inventionwherein signal and power/ground contactors comprise tubular connectorssuch as signal tubular connector 476 and power/ground tubular connector474, respectively. As shown in FIG. 4D, tubular connectors 474 and 476are held in the centers of through holes in a stack of contactor holderplates 464 ₁-464 ₂ by dielectric sheet 466. In accordance with one ormore embodiments of the present invention, one or more of contactorholder plates 464 ₁-464 ₂ are thermally conductive, and in accordancewith one or more further embodiments of the present invention, one ormore of contactor holder plates 464 ₁-464 ₂ are electrically conductive.In accordance with one or more such further embodiments of the presentinvention, contactor holder plates 464 ₁-464 ₂ may be insulated toprevent electrical shorts to tubular connector 474 and 476. Inaccordance with one or more such further embodiments, a dielectricinsulation may extend over all or portions of surfaces of the contactorholder plate(s). In accordance with one or more such furtherembodiments, the insulation for each contactor holder plates 464 ₁-464 ₂may be provided by a thin, conformal layer of anodized aluminum.

As still further shown in FIG. 4D, and in accordance with one or moreembodiments of the present invention, contactor holder plates 464 ₁-464₂ are stacked and have a spacing between them at thinned sections 468 ₁and 468 ₂ in a region disposed about tubular connector 476 that isdesigned to achieve a characteristic impedance of about fifty (50) ohmsfor tubular connector 476. Thus, in accordance with one or more suchembodiments, the thickness of contactor holder plates 464 ₁-464 ₂ aboutcertain contactors may be different than it is about other contactors toadjust the impedance of certain contactors. In addition, a diameter ofthe through hole for tubular connector 474 is smaller than 2.3 times theOD of tubular connector 476, as might be the case for certainembodiments wherein a through hole exists in a solid contactor holderplate(s), i.e., a configuration of contactor holder plate(s) not havingspacing between contactor holder plates shown in FIG. 4D. In furtheraddition, and in accordance with one or more such embodiments of thepresent invention, the spacing between conductive contactor holderplates 464 ₁-464 ₂ can be filled with air, dielectric coatings on theplates, or by a dielectric layer. In accordance with one or more suchembodiments, the dielectric coatings or layer may extend over all orportions of surfaces of the contactor holder plate(s). Lastly, inaccordance with one or more embodiments of the present invention, and asshown in FIG. 4D, channels 486 ₁-486 ₄ in contactor holder plates 464₁-464 ₂ may be used circulate a thermal transfer fluid injected thereinthrough aperture 480.

FIGS. 5A-5D show partial top views of sockets 500-530, respectively,that are fabricated in accordance with one or more embodiments of thepresent invention having various arrangements of signal contactors andpower/ground contactors—as shown in these figures, a signal contactorhas a relatively larger space between a signal contactor body and itscorresponding through hole than that between a power/ground contactorbody and its corresponding through hole. FIG. 5A shows socket 500wherein contactors are arranged in a square array with alternatingsignal and power/ground contactors. This arrangement enables a closerspacing than an arrangement in which signal contactors are directlyadjacent. FIG. 5B shows socket 510 having the same arrangement as socket500 shown in FIG. 5A. However, the through holes for the contactorholder plate of socket 510 for signal contactors are polygonal toprovide a higher signal impedance than can be obtained with a circular,cylindrical hole. FIG. 5C shows socket 520 wherein two signal contactorsare disposed in the same through hole where they are arranged in a pairfor differential signaling applications. Lastly, FIG. 5D shows socket530 wherein signal contactors and power/ground contactors are arrangedin an alternating hexagonal pattern.

FIGS. 6A and 6B are perspective views of tubular contactors 18 and 28having prongs adapted to grip a terminal bump that may be used tofabricate embodiments of the present invention. As shown in FIG. 6A,tubular contactor 1018 comprises a cylindrical metal tube that is cutthrough by helical groves 1010 to form four prongs 1012 terminated infour tips 1014. Prongs 1012 are attached to, and held in place by,cylindrical collar 1016, and are adapted to grip a cylindrical postinserted along a longitudinal axis of tubular contactor 1018. Inaccordance with one embodiment, tubular contactor 1018 is made from a304 stainless steel tube having a 0.44 mm inner diameter and a 0.55 mmouter diameter that is available from K-tube Corporation of Poway,Calif. Four helical grooves 1010 are cut in 0.02 mm wide cut lines alonga 0.75 mm length of the tube using a Nd-YAG laser. Grooves 1010 are cutat an angle of 35° with respect to a circumference of tube 1016. Thelaser cut tube may be plated with a 0.004 mm thick layer of nickel and a0.002 mm thick layer of soft gold to form a conductive surface forcontacting a bump. This embodiment of tubular contactor 1018 is adaptedto connect with a 0.5 mm metal ball. In accordance with one or more suchembodiments, the ball is a steel ball plated with a flash of nickel and0.002 mm of soft gold. A force of 20 gf is sufficient to insert the 0.5mm diameter metal ball into the contactor and to provide a contactresistance of about 0.018 ohms. Once engaged, the ball is held in placeby the contactor without need of a clamp or other mechanical holder.

In accordance with one or more embodiments of the present invention, thethickness of the tubing material of the contactor may be selected tosupply a predetermined insertion force for insertion of a bump into thecontactor, and is preferably between 2% and 20% of the inner diameter ofthe tube. As one of ordinary skill in the art can readily appreciate,the thickness and material of the cylindrical tube may vary dependingupon requirements of a particular application. For example and withoutlimitation, the material may be selected from one or more of, forexample and without limitation, stainless steel of various types,tempered steels, beryllium copper, phosphor bronze, copper alloys ofvarious types, nickel tungsten alloys, nickel chromium alloys, nickelmanganese, nickel binary and ternary alloys, titanium alloys, Nitinol,and other spring materials. In addition, the contactor may be platedwith copper, nickel, cobalt, palladium, gold, alloys thereof as well asother conductive films. In accordance with one or more embodiments, aconnector lubricant may be applied to a surface of the prongs of thecontactor.

Although tubular contactor 1018 has four prongs 1012, it should be clearto one of ordinary skill in the art that further embodiments of thecontactor may incorporate any number of prongs. For example, contactor1028 shown in FIG. 6B has two prongs 1024 with distal ends ending intips 1022 and with proximal ends attached to cylindrical collar 1026.Prongs 1024 may be formed by cutting helical grooves through a wall of acylindrical tube. The insertion force for mating a bump with contactor1028 depends upon an angle of cut line 1020, which angle is preferablybetween 10 and 70 degrees. In accordance with one or more furtherembodiments of the present invention, the angle of cut line 1020 may bevaried with axial distance along contactor 1028. For example and withoutlimitation, in accordance with one or more such embodiments: (a) thesense of the angle of the helical cut may be alternated from positive tonegative to reduce self inductance of the contactor; or (b) the sense ofthe line may be varied over an axial distance to produce a serpentinecut line. In addition, in accordance with one or more furtherembodiments of the present invention, cut line 1020 may vary in widthalong the axial length of the cut.

In addition, as one of ordinary skill in the art will readilyappreciate, embodiments of the present invention may be fabricated byutilizing, for example and without limitation, laser cutting of tubularmaterial, plasma etching of tubular material, pattern etching of tubularmaterial, pattern plating of tubular material, layer plating of tubularmaterial, LIGA plating, and combinations thereof. The tubing of thecontactor is typically a cylinder of circular, oblong, square, orpolygonal cross section. In accordance with one or more furtherembodiments, the contactor may be fabricated as part of a substratecarrier structure. In addition, laser annealing, flash annealing, ionbeam treatment, pickling, quenching, heat treating and other treatmentsthat are well known in the art may be used to improve spring propertiesof the contactor.

FIGS. 7A, 7B and 7C show embodiments of a contactor in which a bottomend may be equivalent to a top end in that the mechanical force neededto mate the top end of the contactor to a terminal bump is substantiallythe same as the mechanical force needed to mate the bottom end to asimilar terminal bump. In accordance with one or more such embodiments,a variety of prong shapes may provide equivalent mating forces to abump. For example, FIG. 7A shows a double ended contactor in which fourprongs on each end form a right handed helix. FIG. 7B shows a doubleended contactor in which four prongs on the top end form a right handedhelix and four prongs on the bottom end form a left handed helix. FIG.7C shows a double ended contactor in which four prongs on the top endand four prongs on the bottom end form an angle with a longitudinal axisof the contactor that varies with distance along the axis to form azigzag pattern. One of ordinary skill in the art will readily appreciatethat a double-ended contactor may be fabricated in accordance with oneor more embodiments wherein ends are mechanically equivalent. Forexample, in certain applications it is desirable that one end of acontactor remain firmly attached to a mating bump while the opposite endis easily disengaged from its mating bump.

One of ordinary skill in the art will readily appreciate that thematerials and fabrication techniques described above with respect totubular connectors 1018 and 1028 may be used to fabricate tubularconnectors described above in conjunction with FIGS. 3A, 4C and 4D.

Further embodiments of the present invention may be fabricated wherein,for through holes having substantially circular cross sections andcontactor bodies having substantially circular cross sections,(D_(signal hole)/D_(signal body))>1.18*(D_(power hole)/D_(power body)),where: (a) D_(signal hole) is a diameter of a through hole for a signalcontactor; (b) D_(signal body) is a diameter of a contactor body for asignal contactor; (c) D_(power hole) is a diameter of a through hole forpower or ground contactor; and (d) D_(power body) is a diameter of acontactor body for a power or ground terminal contactor. In addition,still further embodiments exist wherein: (a) the signal contactorthrough hole cross sectional area is an average signal contactor throughhole cross sectional area over a length of one or more signal contactorthrough holes (and the average signal contactor through hole crosssection is substantially circular with diameter D_(av-signal hole)); (b)the signal contactor body cross sectional area is a maximum signalcontactor body cross sectional area of one or more signal contactors(and the maximum signal contactor body cross section is substantiallycircular with diameter D_(max-signal body)); (c) the power or groundcontactor through hole cross sectional area is an average power orground contactor through hole cross sectional area over a length of oneor more power or ground through holes (and the average power or groundcontactor through hole cross section is substantially circular withdiameter D_(av-power hole)); (d) the power or ground contactor bodycross sectional area is a maximum power or ground contactor body crosssectional area of one or more power or ground contactors (and themaximum power or ground contactor body cross section is substantiallycircular with diameter D_(max-power body)); and (e)(D_(av-signal hole)/D_(max-signal body))>1.18*(D_(av-power hole)/D_(max-power body)).

Further embodiments of the present invention may be fabricated wherein(A_(signal hole)/A_(signal body))>1.4*(A_(power hole)/A_(power body)),where: (a) A_(signal hole) is a cross sectional area of a through holefor a signal contactor; (b) A_(signal body) is a cross sectional area ofa contactor body for a signal contactor; (c) A_(power hole) is a crosssectional area of a through hole for power or ground contactor; and (d)A_(power body) is a cross sectional area of a contactor body for a poweror ground terminal contactor. In embodiments wherein a cross sectionalarea of a through hole or a cross sectional area of a contactor bodyvaries with distance along an axis of the contactor (for example, alonga longitudinal axis), the ratio A_(contactor body)/A_(through ole) maybe estimated to be an average of a ratioA_(contactor bod)/A_(through ole) as measured along the axis of thecontactor (for example, a longitudinal axis).

As has been described above, one or more embodiments of the presentinvention may be fabricated wherein one or more power and/or groundcontactors are disposed in one or more through holes in one or morecontactor plates to provide a predetermined thermal conductivity betweenthe one or more power and/or ground contactors and one or more of theone or more contactor holder plates. Further, in accordance with one ormore further such embodiments, one or more signal contactors aredisposed in one or more through holes in the one or more contactorplates to provide a predetermined characteristic impedance. Stillfurther, in accordance with one or more still further such embodiments,the characteristic impedance of the power and/or ground contactors maybe a predetermined fraction of the characteristic impedance of thesignal contactors (for example and without limitation, less than 80%).As has been discussed above, the characteristic impedance of a contactormay be adjusted, among other things, by adjusting a thickness ofcontactor holder plates disposed thereabout. Hence, one or moreembodiments of the present invention may have: (a) a cross sectionalarea of one or more through holes for one or more power and/or groundcontactors be the same or about the same as a cross sectional area ofone or more through holes for one or more signal contactors; and (b) across sectional area of a body of the one or more power and/or groundcontactors may be same or about the same as a cross sectional area of abody of the one or more signal contactors; however, the thickness of oneor more of the one or more contactor holder plates in a region about theone or more signal contactors may be adjusted to provide a predeterminedcharacteristic impedance—for example, such thickness may be differentfrom the thickness of the one or more of the one or more contactorholder plates in a region about the one or more power and/groundcontactors.

As one of ordinary skill in the art can readily appreciate from theabove, one or more further embodiments of the present invention may befabricated (for example and without limitation, from one or more of theabove-described embodiments) wherein top and/or bottom ends of contactorbodies are disposed in through holes so that they extend beyond: (a) topand/or bottom surfaces of one or more (or all) of the contactor holderplate(s); and/or (b) top and/or bottom surfaces of any dielectric sheetsbetween which contactor holder plate(s) may be disposed.

As one of ordinary skill in the art can readily appreciate, inaccordance with many of the above-described embodiments, the contactorbodies do not contact the contactor holder plate(s). Further, inaccordance with many of such above-described embodiments, protuberanceson the contactor bodies do not contact the contactor holder plate(s).

Embodiments of the present invention described above are exemplary. Assuch, many changes and modifications may be made to the disclosure setforth above while remaining within the scope of the invention. Inaddition, materials, methods, and mechanisms suitable for fabricatingembodiments of the present invention have been described above byproviding specific, non-limiting examples and/or by relying on theknowledge of one of ordinary skill in the art. Materials, methods, andmechanisms suitable for fabricating various embodiments or portions ofvarious embodiments of the present invention described above have notbeen repeated, for sake of brevity, wherever it should be wellunderstood by those of ordinary skill in the art that the variousembodiments or portions of the various embodiments could be fabricatedutilizing the same or similar previously described materials, methods ormechanisms. Further, as is apparent to one skilled in the art, theembodiments may be used for making connections to semiconductor devices,electronic devices, electronic subsystems, cables, and circuit boardsand assemblies.

As one or ordinary skill in the art will readily appreciate, socketsfabricated in accordance with one or more embodiments of the presentinvention may include any number of fluid seals, gaskets, adhesives,washers, or other elements that function to seal the assembly and toprevent thermal transfer fluid from leaking (internally or externally).

The scope of the invention should be determined with reference to theappended claims along with their full scope of equivalents.

1. A socket useful to contact an electronic device, the socketcomprising: a structure comprised of one or more metallic contactorholder plates, the structure including one or more first through holeshaving a first hole cross sectional area, and one or more second throughholes having a second hole cross sectional area, which one or more firstthrough holes and one or more second through holes extend through eachof the one or more metallic contactor holder plates of the structure;one or more first contactors having a body with a first body crosssectional area, which body is disposed in the first through holes; oneor more second contactors having a body with a second body crosssectional area, which body is disposed in the second through holes; anda heat sink in thermal contact with one or more of the one or morecontactor holder plates; wherein: the first hole cross sectional area isan average first hole cross sectional area over a length of the one ormore first through holes; the second hole cross sectional area is anaverage second hole cross sectional area over a length of the one ormore second through holes; the first body cross sectional area is one ofan average or a maximum first body cross sectional area over a length ofthe body of the one or more first contactors; the second body crosssectional area is one of an average or a maximum second body crosssectional area over a length of the body of the one or more secondcontactors; and a first ratio of the first hole cross sectional area tothe first body cross sectional area is different from a second ratio ofthe second hole cross sectional area to the second body cross sectionalarea.
 2. The socket of claim 1 wherein the first body cross sectionalarea is the same as the second body cross sectional area.
 3. The socketof claim 1 wherein the first hole cross sectional area is the same asthe second hole cross sectional area.
 4. The socket of claim 1 whereinthe first hole cross sectional area is different from the second holecross sectional area, and the first body cross sectional area isdifferent from the second body cross sectional area.
 5. The socket ofclaim 1 wherein one or more of the one or more metallic contactor holderplates is made of one or more of copper, bronze, a copper alloy, acopper plated nickel-iron alloy, a silver alloy, aluminum, or analuminum alloy.
 6. The socket of claim 1 wherein the heat sink includeschannels adapted to direct a thermal transfer fluid therethrough.
 7. Thesocket of claim 6 wherein the thermal transfer fluid is a liquid.
 8. Thesocket of claim 7 wherein the liquid is one or more of water,water-glycol mixtures, Fluorinert, or Galden®.
 9. The socket of claim 6wherein the thermal transfer fluid is a gas.
 10. The socket of claim 9wherein the gas is one or more of compressed air, air, nitrogen, andhelium.
 11. The socket of claim 1 wherein one or more of the contactorsis a spring probe.
 12. The socket of claim 11 where the spring probe isa Pogo® spring contact.
 13. The socket of claim 1 wherein one or more ofthe contactors is a tubular connector.
 14. The socket of claim 1 whereinthe heat sink is integral with one or more of the contactor holderplates.
 15. The socket of claim 1 wherein the heat sink is adapted totransfer heat to a flow of air.
 16. The socket of claim 15 wherein theflow of air is convective flow.
 17. The socket of claim 16 wherein theheat sink includes surface protrusions.
 18. The socket of claim 1wherein: the average or the maximum first body cross sectional areaexcludes protuberances extending from the first contactors that occupyless than 10 percent of a surface area of the first contactor body; andthe average or the maximum second body cross sectional area excludesprotuberances extending from the second contactors that occupy less than10 percent of a surface area of the first contactor body.
 19. The socketof claim 1 wherein: the first hole cross section, the first body crosssection, the second hole cross section, the second body cross sectionare substantially circular; and a first ratio of a diameter of the firsthole cross section to a diameter of the first body cross section is morethan 1.18 times a second ratio of a diameter of the second hole crosssection to a diameter of the second body cross section.
 20. The socketof claim 19 wherein the first ratio is about 2.3 and the second ratio isless than
 2. 21. The socket of claim 1 wherein: an average first holecross section corresponding to the average first hole cross sectionalarea, a maximum first body cross section corresponding to the maximumfirst body cross sectional area, an average second hole cross sectioncorresponding to the average second hole cross sectional area, and amaximum second body cross section corresponding to the maximum secondbody cross sectional area are substantially circular; and a first ratioof a diameter of the average first hole cross section to a diameter ofthe maximum first body cross section is more than 1.18 times a secondratio of a diameter of the average second hole cross section to adiameter of the maximum second body cross section.
 22. The socket ofclaim 21 wherein the first ratio is about 2.3 and the second ratio isless than
 2. 23. The socket of claim 1 further comprising: one or moredielectric materials disposed between one or more of the contactorholder plates.
 24. The socket of claim 1 further comprising: dielectricmaterial disposed on a surface of one or more of the one or more throughholes.
 25. The socket of claim 1 further comprising: a top dielectriclayer disposed over the one or more contactor plates, and a bottomdielectric layer disposed under the one or more contactor plates, thetop dielectric layer and the bottom dielectric layers having throughholes through which a portion of the first contactors and secondcontactors is disposed.
 26. The socket of claim 1 wherein one or more ofthe one or more contactor holder plates have a first thickness in afirst region disposed about one or more of the one or more first throughholes and a second thickness in a second region disposed about one ormore of the one or more second through holes, and the first thickness isdifferent from the second thickness.
 27. The socket of claim 1 whereintwo of the one or more first contactors are disposed in one of the oneor more first through holes.
 28. A socket useful to contact anelectronic device, the socket comprising: a structure comprised of oneor more metallic contactor holder plates, the structure including one ormore first through holes having a first hole cross sectional area, andone or more second through holes having a second hole cross sectionalarea, which one or more first through holes and one or more secondthrough holes extend through each of the one or more contactor holderplates of the structure; one or more first contactors having a body witha first body cross sectional area, which body is disposed in the firstthrough holes; one or more second contactors having a body with a secondbody cross sectional area, which body is disposed in the second throughholes; and a heat sink in thermal contact with one or more of the one ormore contactor holder plates; wherein; the first hole cross sectionalarea is an average first hole cross sectional area over a length of theone or more first through holes; the second hole cross sectional area isan average second hole cross sectional area over a length of the one ormore second through holes; the first body cross sectional area is one ofan average or a maximum first body cross sectional area over a length ofthe body of the one or more first contactors; the second body crosssectional area is one of an average or a maximum second body crosssectional area over a length of the body of the one or more secondcontactors; a first ratio of the first hole cross sectional area to thefirst body cross sectional area is different from a second ratio of thesecond hole cross sectional area to the second body cross sectionalarea; and an aperture is provided for introduction of thermal transferfluid between two or more of the contactor holder plates.
 29. A socketuseful to contact an electronic device, the socket comprising: astructure comprised of one or more electrically conductive contactorholder plates, the structure including one or more first through holeshaving a first hole cross sectional area, and one or more second throughholes having a second hole cross sectional area, which one or more firstthrough holes and one or more second through holes extend through eachof the one or more contactor holder plates of the structure; one or morefirst contactors having a body with a first body cross sectional area,which body is disposed in the first through holes; one or more secondcontactors having a body with a second body cross sectional area, whichbody is disposed in the second through holes; and a heat sink in thermalcontact with one or more of the one or more contactor holder plates;wherein: the first hole cross sectional area is an average first holecross sectional area over a length of the one or more first throughholes; the second hole cross sectional area is an average second holecross sectional area over a length of the one or more second throughholes; the first body cross sectional area is one of an average or amaximum first body cross sectional area over a length of the body of theone or more first contactors; the second body cross sectional area isone of an average or a maximum second body cross sectional area over alength of the body of the one or more second contactors; and a ratio ofthe first hole cross sectional area to the first body cross sectionalarea is greater than 1.4 times a ratio of the second hole crosssectional area to the second body cross sectional area.
 30. The socketof claim 29 wherein one or more of the one or more contactor holderplates have a first thickness in a first region disposed about one ormore of first through holes and a second thickness in a second regiondisposed about one or more of the one or more second through holes, andthe first thickness is different from the second thickness.
 31. Thesocket of claim 29 wherein two of the one or more first contactors aredisposed in one of the one or more first through holes.
 32. The socketof claim 29 wherein: the average or the maximum first body crosssectional area excludes protuberances extending from the firstcontactors that occupy less than 10 percent of a surface area of thefirst contactor body; and the average or the maximum second body crosssectional area excludes protuberances extending from the secondcontactors that occupy less than 10 percent of a surface area of thefirst contactor body.
 33. The socket of claim 29 further comprising: oneor more dielectric materials disposed between one or more of thecontactor holder plates.
 34. The socket of claim 29 further comprising:dielectric material disposed on a surface of one or more of the one ormore through holes.
 35. The socket of claim 29 further comprising: a topdielectric layer disposed over the one or more contactor plates, and abottom dielectric layer disposed under the one or more contactor plates,the top dielectric layer and the bottom dielectric layers having throughholes through which a portion of the first contactors and secondcontactors is disposed.
 36. A socket useful to contact an electronicdevice, the socket comprising: a structure comprised of one or moreelectrically conductive contactor holder plates, the structure includingone or more first through holes having a first hole cross sectionalarea, and one or more second through holes having a second hole crosssectional area, which one or more first through holes and one or moresecond through holes extend through each of the one or more contactorholder plates of the structure; one or more first contactors having abody with a first body cross sectional area, which body is disposed inthe first through holes; one or more second contactors having a bodywith a second body cross sectional area, which body is disposed in thesecond through holes; and wherein: the first hole cross sectional areais an average first hole cross sectional area over a length of the oneor more first through holes; the second hole cross sectional area is anaverage second hole cross sectional area over a length of the one ormore second through holes; the first body cross sectional area is one ofan average or a maximum first body cross sectional area over a length ofthe body of the one or more first contactors; the second body crosssectional area is one of an average or a maximum second body crosssectional area over a length of the body of the one or more secondcontactors; a ratio of the first hole cross sectional area to the firstbody cross sectional area is greater than 1.4 times a ratio of thesecond hole cross sectional area to the second body cross sectionalarea; and an aperture is provided for introduction of thermal transferfluid between two or more of the contactor holder plates.
 37. The socketof claim 29 wherein the first body cross sectional area is the same asthe second body cross sectional area.
 38. The socket of claim 29 whereinthe first hole cross sectional area is the same as the second hole crosssectional area.
 39. The socket of claim 29 wherein the first hole crosssectional area is different from the second hole cross sectional area,and the first body cross sectional area is different from the secondbody cross sectional area.
 40. The socket of claim 29 wherein one ormore of the contactors is a spring probe.
 41. The socket of claim 29wherein one or more of the contactors is a tubular connector.
 42. Asocket useful to contact an electronic device, the socket comprising: astructure comprised of one or more metallic contactor holder plates, thestructure including one or more first through holes having a first holecross sectional area, and one or more second through holes having asecond hole cross sectional area, which one or more first through holesand one or more second through holes extend through each of the one ormore contactor holder plates of the structure; one or more firstcontactors having a body with a first body cross sectional area, whichbody is disposed in the first through holes; one or more secondcontactors having a body with a second body cross sectional area, whichbody is disposed in the second through holes; and a heat sink in thermalcontact with one or more of the one or more contactor holder plates;wherein: the first hole cross sectional area is an average first holecross sectional area over a length of the one or more first throughholes; the second hole cross sectional area is an average second holecross sectional area over a length of the one or more second throughholes; the first body cross sectional area is one of an average or amaximum first body cross sectional area over a length of the body of theone or more first contactors; the second body cross sectional area isone of an average or a maximum second body cross sectional area over alength of the body of the one or more second contactors; the body of theone or more first contactors does not contact the one or more contactorholder plates; and the body of the one or more second contactors doesnot contact the one or more contactor holder plates.
 43. The socket ofclaim 42 wherein the first hole cross sectional area is different fromthe second hole cross sectional area.
 44. The socket of claim 43 whereinthe first body cross sectional area is the same as the second body crosssectional area.
 45. The socket of claim 42 wherein the first hole crosssectional area is the same as the second hole cross sectional area. 46.The socket of claim 45 wherein the first body cross sectional area isdifferent from the second body cross sectional area.
 47. The socket ofclaim 42 wherein the first hole cross sectional area is different fromthe second hole cross sectional area, and the first body cross sectionalarea is different from the second body cross sectional area.
 48. Thesocket of claim 42 wherein one or more of the one or more metalliccontactor holder plates is made of one or more of copper, bronze, acopper alloy, a copper plated nickel-iron alloy, a silver alloy,aluminum, or an aluminum alloy.
 49. The socket of claim 42 furthercomprising: one or more dielectric materials disposed between one ormore of the contactor holder plates.
 50. The socket of claim 42 furthercomprising: dielectric material disposed on a surface of one or more ofthe one or more through holes.
 51. The socket of claim 42 furthercomprising: a top dielectric layer disposed over the one or morecontactor plates, and a bottom dielectric layer disposed under the oneor more contactor plates, the top dielectric layer and the bottomdielectric layers having through holes through which a portion of thefirst contactors and second contactors is disposed.
 52. A socket usefulto contact an electronic device, the socket comprising: a structurecomprised of one or more contactor holder plates, structure includingone or more first through holes having a first hole cross sectionalarea, and one or more second through holes having a second hole crosssectional area, which one or more first through holes and one or moresecond through holes extend through each of the one or more contactorholder plates of the structure; one or more first contactors having abody with a first body cross sectional area, which body is disposed inthe first through holes; one or more second contactors having a bodywith a second body cross sectional area, which body is disposed in thesecond through holes; and a heat sink in thermal contact with one ormore of the one or more contactor holder plates; wherein: the first holecross sectional area is an average first hole cross sectional area overa length of the one or more first through holes; the second hole crosssectional area is an average second hole cross sectional area over alength of the one or more second through holes; the first body crosssectional area is one of an average or a maximum first body crosssectional area over a length of the body of the one or more firstcontactors; the second body cross sectional area is one of an average ora maximum second body cross sectional area over a length of the body ofthe one or more second contactors; the body of the one or more firstcontactors does not contact the one or more contactor holder plates; thebody of the one or more second contactors does not contact the one ormore contactor holder plates; and an aperture is provided forintroduction of thermal transfer fluid between two or more of thecontactor holder plates.
 53. A socket useful to contact an electronicdevice, the socket comprising: a structure comprised of one or moremetallic contactor holder plates, the structure including one or morefirst through holes having a first hole cross sectional area, and one ormore second through holes having a second hole cross sectional area,which one or more first through holes and one or more second throughholes extend through each of the one or more contactor holder plates ofthe structure; one or more first contactors having a body with a firstbody cross sectional area, which body is disposed in the first throughholes; one or more second contactors having a body with a second bodycross sectional area, which body is disposed in the second throughholes; and a heat sink in thermal contact with one or more of the one ormore contactor holder plates; wherein: the first hole cross sectionalarea is an average first hole cross sectional area over a length of theone or more first through holes; the second hole cross sectional area isan average second hole cross sectional area over a length of the one ormore second through holes; the first body cross sectional area is one ofan average or a maximum first body cross sectional area over a length ofthe body of the one or more first contactors; the second body crosssectional area is one of an average or a maximum second body crosssectional area over a length of the body of the one or more secondcontactors; and the first hole cross sectional area is different fromthe second hole cross sectional area.
 54. The socket of claim 53 whereinthe first body cross sectional area is different from the second bodycross sectional area.
 55. A socket useful to contact an electronicdevice, the socket comprising: a structure comprised of one or moremetallic contactor holder plates, the structure including one or morefirst through holes having a first hole cross sectional area, and one ormore second through holes having a second hole cross sectional area,which one or more first through holes and one or more second throughholes extend through each of the one or more contactor holder plates ofthe structure; one or more first contactors having a body with a firstbody cross sectional area, which body is disposed in the first throughholes; one or more second contactors having a body with a second bodycross sectional area, which body is disposed in the second throughholes; and a heat sink in thermal contact with one or more of the one ormore contactor holder plates; wherein: the first hole cross sectionalarea is an average first hole cross sectional area over a length of theone or more first through holes; the second hole cross sectional area isan average second hole cross sectional area over a length of the one ormore second through holes; the first body cross sectional area is one ofan average or a maximum first body cross sectional area over a length ofthe body of the one or more first contactors; the second body crosssectional area is one of an average or a maximum second body crosssectional area over a length of the body of the one or more secondcontactors; and the first body cross sectional area is different fromthe second body cross sectional area.
 56. The socket of claim 55 whereinthe first hole cross sectional area is different from the second holecross sectional area.
 57. A socket useful to contact an electronicdevice, the socket comprising: a structure comprised of one or moremetallic contactor holder plates, the structure including one or morefirst through holes having a first hole cross sectional area, and one ormore second through holes having a second hole cross sectional area,which one or more first through holes and one or more second throughholes extend through each of the one or more contactor holder plates ofthe structure; one or more first contactors having a body with a firstbody cross sectional area, which body is disposed in the first throughholes; one or more second contactors having a body with a second bodycross sectional area, which body is disposed in the second throughholes; and a heat sink in thermal contact with one or more of the one ormore contactor holder plates; wherein: the first hole cross sectionalarea is an average first hole cross sectional area over a length of theone or more first through holes; the second hole cross sectional area isan average second hole cross sectional area over a length of the one ormore second through holes; the first body cross sectional area is one ofan average or a maximum first body cross sectional area over a length ofthe body of the one or more first contactors; the second body crosssectional area is one of an average or a maximum second body crosssectional area over a length of the body of the one or more secondcontactors; and one or more of the one or more contactor holder plateshave a first thickness in a first region disposed about one or more ofthe first through holes and a second thickness in a second regiondisposed about one or more of the second through holes, and the firstthickness is different from the second thickness.
 58. The socket ofclaim 57 wherein the first body cross sectional area is the same as thesecond body cross sectional area.
 59. The socket of claim 57 wherein thefirst hole cross sectional area is the same as the second hole crosssectional area.
 60. The socket of claim 57 wherein the first hole crosssectional area is different from the second hole cross sectional area,and the first body cross sectional area is different from the secondbody cross sectional area.
 61. The socket of claim 57 wherein one ormore of the contactors is a spring probe.
 62. The socket of claim 57wherein one or more of the contactors is a tubular connector.
 63. Thesocket of claim 57 wherein: one or more of the one or more firstcontactors have a first characteristic impedance; one or more of the oneor more second contactors have a second characteristic impedance; andthe second characteristic impedance is no greater 80 percent of thefirst characteristic impedance.
 64. A socket useful to contact anelectronic device, the socket comprising: a structure comprised of oneor more electrically conductive contactor holder plates, the structureincluding one or more first through holes, and one or more secondthrough holes, which one or more first through holes and one or moresecond through holes extend through each of the one or more contactorholder plates of the structure; one or more first contactors aredisposed in the first through holes; one or more second contactors aredisposed in the second through holes; and a heat sink in thermal contactwith one or more of the one or more contactor holder plates; wherein:one or more of the one or more first contactors have a firstcharacteristic impedance; one or more of the one or more secondcontactors have a second characteristic impedance; and the secondcharacteristic impedance is no greater 80 percent of the firstcharacteristic impedance.